Reactive distillation for producing ethyl propionate featured with extreme excess of propionic acid: Process design and analysis

Abstract Aiming at the problem of high energy consumption in traditional water‐carrying agent process for producing ethyl propionate, based on the thermodynamic analysis of residual curve map, a low energy consumption strategy for producing ethyl propionate via reactive distillation was proposed featured with extreme excess of propionic acid. It could realize the complete conversion (>99%) of ethanol via thermodynamic driving from propionic acid excess and facilitate effective separation of the water‐ethyl propionate distillate which forms two immiscible liquid phases and enables simple decantation with 98% EP recovery from organic phase through natural phase stratification, leading to significant reduction in energy consumption. A comprehensive investigation of process design and analysis for high‐purity ethyl propionate production with extreme excess of propionic acid was carried out by integrating process simulation and experimental validation in this work. Parametric studies of reactive distillation including excessive degree of propionic acid, holdup in bottom kettle reboiler, number of theoretical plates, and reflux ratio on the process performance and energy consumption was investigated. Simulation results of this new process were validated through experiments. Subsequently, the energy‐saving designs of further EP and water purification were implemented, including a weak alkaline solution washing to remove trace propionic acid from the distillate and distillation for separation of ethyl propionate and water. Finally, under preferred conditions, the proposed process with molar ratio of propionic acid to ethanol of 30:1, only required about 1700 kJ/kg for producing high‐purity ethyl propionate (0.99999), saving 68% energy consumption by comparison with the traditional process.